Merge tag 'v4.4.12' into linux-linaro-lsk-v4.4

 This is the 4.4.12 stable release

2 files changed, 26 insertions, 16 deletions

diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
index e2aadbc7151f..7d633f19e38a 100644
--- a/include/asm-generic/qspinlock.h
+++ b/include/asm-generic/qspinlock.h
@@ -27,7 +27,30 @@
  */
 static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
 {
-	return atomic_read(&lock->val);
+	/*
+	 * queued_spin_lock_slowpath() can ACQUIRE the lock before
+	 * issuing the unordered store that sets _Q_LOCKED_VAL.
+	 *
+	 * See both smp_cond_acquire() sites for more detail.
+	 *
+	 * This however means that in code like:
+	 *
+	 *   spin_lock(A)		spin_lock(B)
+	 *   spin_unlock_wait(B)	spin_is_locked(A)
+	 *   do_something()		do_something()
+	 *
+	 * Both CPUs can end up running do_something() because the store
+	 * setting _Q_LOCKED_VAL will pass through the loads in
+	 * spin_unlock_wait() and/or spin_is_locked().
+	 *
+	 * Avoid this by issuing a full memory barrier between the spin_lock()
+	 * and the loads in spin_unlock_wait() and spin_is_locked().
+	 *
+	 * Note that regular mutual exclusion doesn't care about this
+	 * delayed store.
+	 */
+	smp_mb();
+	return atomic_read(&lock->val) & _Q_LOCKED_MASK;
 }
 
 /**
@@ -107,6 +130,8 @@ static __always_inline void queued_spin_unlock(struct qspinlock *lock)
  */
 static inline void queued_spin_unlock_wait(struct qspinlock *lock)
 {
+	/* See queued_spin_is_locked() */
+	smp_mb();
 	while (atomic_read(&lock->val) & _Q_LOCKED_MASK)
 		cpu_relax();
 }
diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h
index 3d1a3af5cf59..a2508a8f9a9c 100644
--- a/include/asm-generic/siginfo.h
+++ b/include/asm-generic/siginfo.h
@@ -17,21 +17,6 @@
 struct siginfo;
 void do_schedule_next_timer(struct siginfo *info);
 
-#ifndef HAVE_ARCH_COPY_SIGINFO
-
-#include <linux/string.h>
-
-static inline void copy_siginfo(struct siginfo *to, struct siginfo *from)
-{
-	if (from->si_code < 0)
-		memcpy(to, from, sizeof(*to));
-	else
-		/* _sigchld is currently the largest know union member */
-		memcpy(to, from, __ARCH_SI_PREAMBLE_SIZE + sizeof(from->_sifields._sigchld));
-}
-
-#endif
-
 extern int copy_siginfo_to_user(struct siginfo __user *to, const struct siginfo *from);
 
 #endif